1. Field of the Invention
The present invention relates to a patient couch used for a diagnostic imaging apparatus, and to a magnetic resonance imaging (MRI) apparatus and an MRI method that perform MRI to a subject that is laid on a patient couch, and in particular, relates to a belt provided to a tabletop of the patient couch to fix the subject, and to an imaging procedure.
2. Description of the Related Art
A diagnostic imaging apparatus, which images a subject to perform a diagnostic imaging, includes a magnetic resonance imaging (MRI) apparatus, an X-ray computed tomography (CT) apparatus, a positron emission tomography (PET) apparatus, an X-ray diagnostic apparatus and the like.
The diagnostic imaging apparatuses such as the MRI apparatus, the X-ray CT apparatus, and the PET apparatus have a gantry that includes an opening formed thereon for performing the imaging. A subject is inserted into the opening and imaged therein. An X-ray diagnostic apparatus, for example, for circulatory organs has an imaging unit that includes an X-ray generator and an X-ray detector placed so as to oppose each other on both ends of a C-shaped arm. A subject is inserted (into the opening) between the X-ray generator and the X-ray detector and imaged therein.
The subject is laid on a tabletop of a patient couch arranged near the opening of the gantry to move the subject on the tabletop into the opening of the diagnostic imaging apparatus, whereby the subject is inserted into the diagnostic imaging apparatus.
In the imaging using the MRI apparatus, an imaging operation usually requires a comparatively long imaging time such as about one to five minutes. If the subject moves during the imaging operation, a blur or a slur occurs in an image. Further, if the subject largely moves, it may become impossible to diagnose. To solve these problems, the subject needs to be fixed appropriately on the tabletop. Conventionally, for example, a belt-shaped fixing tool having a rubber knitted therein, and a flexible material having elasticity, such as a sponge or a towel, to be tucked in the fixing tool, are used together to bind the subject onto the tabletop in a tying manner. As a method for connecting the belt, various methods such as a Velcro tape or a ratchet have been proposed. As a binding method, various methods have been proposed, such as stuffing many flexile materials between the belt and the subject without letting the belt have any elasticity, or increasing shrinkage of the belt. A conventional technology has been disclosed in, for example, JP-A 2006-136618 (KOKAI).
However, all these methods largely depend on the level of performance (e.g., a skill or an experience) of an operator who performs fixing operation. For example, even in fastening the belt, when the belt is locally fixed at only one position, a degree of freedom, which allows a rotation about a fixed region, remains, whereby a motion may occur at a part that is need to be imaged (an imaged part). Appropriately suppressing a body motion of the subject is not easy. For example, when a fixing strength is too weak, the motion cannot be restraint. When the fixing strength is too strong, the subject becomes tired in a last half period of the imaging, thereby inducing a reflective involuntary action of a muscle or the like, which makes the subject move.